Age and sex effects in killifish inner ear hair cells. (a) Representative confocal images of inner ear epithelia from a 2-month-old (top row) and a 5-month-old (bottom row) adult killifish. The scale bar in the top left image applies to all images. (b) Quantification of phalloidin-labeled hair bundles from 2-month-old (green bars), 3-month-old (white bars) and 4–6-month-old (gray bars) killifish epithelia. Hair bundles were counted in three 50 X 50 µm ROI per epithelium for the saccule and two 50 X 50 µm ROI for the utricle and lagena. The data show the sum of all ROI for a given epithelium. There is no significant effect of age on hair bundle density (2-way ANOVA, main effect of age F2,101 = 0.112, p = 0.894). Data are presented as mean ± 1 s.d. and dots represent individual fish. (c) Linear regression of saccular hair cells by age for male (left) and female (right) killifish. The slope is significantly different from zero for males (F1,21 = 4.78, p = 0.0402) but not females (F1,15 = 0.06, p = 0.8166). N = 7–8 2-month old females, n = 7–8 2-month old males, n = 4–6 3-month-old males, n = 9 4–6-month-old females, n = 7–9 4–6-month-old males.
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